| The walking mechanism is a key part of shearer,which directly influences the mining efficiency and working reliability of the machine.The walking mechanism holds complex structure and works under complicated and changing loads,so that fatigue fracture or wear failure accidents usually occur at guide slippers,flat slippers and pin rails.Therefore,according to the above mentioned problems,researches of this study are complemented taking the mechanical test and analysis platform of large scale shearer at "Nation Energy Coal Mining Machinery and Equipment Research and Development Experiment Center" as exmperimental basis.Researched contents are listed as follows:The dynamic relationships between the shearer and the conveyor are described according to deformation compatibility principle.Based on that,the static equations for the whole machine are built.Taking roller force as input data,the interaction forces between the walking mechanism and the conveyor are solved.The results are then checked by experiments.The statics mechanism between the walking mechanism and the conveyor is revealed.Based on dry sliding theories,the contact dynamics model between the flat slippers of shearer and spade plates of conveyor is built.The non-linear driving model between driving gear and pin rail is built by using the non-linear meshing dynamic model of gear pairs with clearance.The contact impact dynamics model between guide slipper and pin rail is built by using clearance dynamic theories.According to those models,the two dynamics models of the shearer in vertical and walking direction are built.The models are solved by numerical analysis method.The results are then checked by experiments.The coupled contact dynamics mechanism between the walking mechanism and the conveyor is revealed.The 1:1 simulating test platform of completed set equipment of fully mechanized coal mining face for integrative machanical test in "Nation Energy Coal Mining Machinery and Equipment Research and Development Experiment Center" is used for related experimental research.The dynamic characterizations are obtained by setting up pin axis sensors to cutting parts of shearer,transmission system of walking parts,flat slippers and guide slippers.Then the dynamic transmission models between the shearer and the conveyor are checked and the load spectra of the flat slippers and the guide slippers are obtained.Then the attribute data of the flat slippers and the guide slippers are analyzed.Those works can provide reliable and sufficient experimental materials and theoretical basis.The surface wear failure mode of slippers,pin rails and spade plates under low speed and high load is investigated.By experimental method,the change law of wear volume influenced by load under experimental condition for sliding materials of slippers,pin rails and spade plates is studied.The calculating equations for non-dimensional wear rate of those materials are obtained.Then the wear failure mechanisms of those two kinds of materials are revealed.Results indicate that:under tested loads,the wear form of those materials is on the regular stage,so that the calculating equations of wear rates can be used for the prediction of wear life for those parts.Taking contact pressure as the variation,the simulation model for the wear volume of those materials is built.The wear failure mechanism under practical condition of the two friction pairs--guide slippers vs.pin rails and flat slippers vs.spade plate--is researched.Then the lifetime reliable prediction model for those materials is built.Taking the MG500/1180-WD shearer as a simulation example,wear life predictions of slippers,pin rails and spade plates under practical condition are studied,and then an improvement plan based on equivalent life theory for increasing the entire wear lifetime of the machine is provided,which can successfully improve the work lifetime and reliability of the machine. |
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